Signs providing warnings and other information are often employed in close proximity to vehicular traffic as well as pedestrians traveling alongside roadways, or on sidewalks. A typical use for such sign panels is to convey a message giving warning or other notice of a nearby traffic obstruction such as a work site. Such message panels must be of a substantial size in order to attract the attention of motorists and pedestrians engaged in what is oftentimes a repetitive course of activity. When signs, particularly relatively large sign panels made of flexible material are placed near a roadside, localized wind gusts from passing vehicles can add substantial impact to naturally occurring wind forces. Accordingly, considerable attention has been paid to stabilize large sign panels, whether made of rigid or flexible material, since the “sail area” of the message panel can capture a substantial force applied by wind loading.
One notable trend in recent years is the increased use of sign panels and other warning devices which are capable of being folded into a compact package so as to be conveniently stored in the trunk of a passenger vehicle. Such packages are also made to fit in a relatively small space, such as an elongated pocket on a work vehicle reserved for stowing temporary signs along side other equipment. Warning devices of these types are typically employed only for brief periods of time and the occasion of their deployment oftentimes cannot be predicted in advance. For example, work crews assigned to work on a portion of roadway or a roadside location must be free to carry out their assignments without undue intrusion from nearby passing vehicles and pedestrians. Accordingly, it is important that suitably impactful messaging be provided to alert motorists and pedestrians to avoid work site areas.
In addition to the relatively large physical size of the message panels deployed, it is important that the orientation of the message panels be optimized with regard to the direction of traffic flow. Accordingly, it is important that the angular orientation of the face of the message panel to the direction of traffic flow be maintained in a constant direction despite wind gusts and other loads applied to the message panel. A message panel of flexible material is usually deployed by being suspended on an open framework. Typically, the framework comprises a scissors or central pivoting connection of a pair of battens, frame members or ribs made of relatively lightweight and somewhat flexible material such as aluminum or a fiberglass. The ribs may be deployed so as to overlie one another, forming a collapsed structure having an elongated shape of minimal cross-sectional size. Typically, the flexible message panel is then rolled around the collapsed ribs, for storage in a long tube or other suitable space provided for the purpose. Deployment proceeds with an initial unrolling of the message panel fabric to expose the ribs, which are then pivoted in a mutually orthogonal position. Typically, one rib arranged in a vertical direction and the other rib arranged in a horizontal direction. The flexible message panel, which is typically of a square configuration, has its corners attached to the end points of the expanded ribs. Because of the relatively delicate nature of the message panel material compared to the applied loadings and the relatively small cross-sectional size of each rib, special precautions have been taken for mounting the corners of message panels to rib ends.
One popular arrangement for securing the corners of message panels is found in U.S. Pat. Nos. 5,446,984; 6,003,827; 4,888,894 and 4,426,800. In these patents, a rigid pocket-like structure, made of plastic or other suitable material is attached to the corners of the message panel. The pocket defines a channel suitable for receiving a rib end. Thus, wind loadings other forces and abrasion from repeated assembly and disassembly is taken up by the plastic pocket structure. It is noted that similar problems arising in different technological areas have provided imaginative solutions. For example, U.S. Pat. No. 4,535,825 discloses an improvement in sail battens, where a pocket sewn in a canvas sail dimensioned to receive the end of a batten, is provided with reinforcements which are held against the end of the batten by the use of a cord secured to a point on the batten, inboard of its free end. U.S. Pat. No. 6,381,889 discloses a cover portion for engaging a batten, which in turn is supported by tracks with which it is engaged.
Flexible straps of toughened material have been employed to secure the corners of message panels with respect to the end portions of supporting battens or ribs. For example, U.S. Pat. No. 4,507,887 employs flexible straps secured to the corners of a message panel which, after being wrapped around the end of a batten, are secured to inboard portions of the batten by snap fasteners. U.S. Pat. No. 4,592,158 further adds the use of hook and loop fastener material to secure the message panel to the battens.
One particular arrangement for securing a flexible message panel to a pair of supporting ribs is described in U.S. Pat. No. 5,152,091. Highway signs constructed generally according to this patent were offered for sale by Pacific Safety Corporation of Salem, Oreg. In this sign arrangement, message panels were provided with flexible straps at their corners for securement to the ends of supporting ribs. Buckle-shaped fasteners are secured at one end of the straps and are provided with an internal opening to permit passage of a rib, therethrough. When deploying a sign panel, the buckle-shaped fasteners are inserted over the free ends of the ribs, and released. In order to maintain the desired tension for the message panel, unwanted inward travel of the buckle-shaped fasteners is prevented by stops or protrusions mounted to the ends of the ribs. The protrusions engage the buckle-shaped fasteners, preventing their further inward travel along the rib. This business concern is now owned and operated by the assignee of the present invention.
With reference to FIGS. 17-19, examination of one type of sign system unit offered for sale by Pacific Safety Corporation revealed that opposed, panel-mounted horizontal straps, while having a somewhat elastic underlying component, were prohibited from stretching because of their incorporation with overlying strap members of woven, inelastic non-extendable material. Essentially, the strap fasteners applied to the message panels operate in a conventional, substantially non-stretchable manner. Referring to FIGS. 17-19 a corner of a prior art sign assembly is shown. In FIG. 17, a corner of a sign panel 2 is provided with an aluminum buckle 5, secured to the sign panel with flexible, elastic layer 6 overlaid by a flexible, but substantially inelastic layer 3. The layers or straps 3, 6 are secured to flexible panel 2 by stitching 4. The longitudinal cross sectional view of FIG. 19 shows the arrangement of FIG. 17 fitted over the free end 8 of a conventional fiberglass rib. A rubber stop 9 is secured to the rib with a rivet fastener, and prevents buckle 5 from further inward travel along the rib (in a rightward direction as shown in FIG. 19). It will be appreciated upon a careful study of FIGS. 17 and 19, that the elastic layer 6 is, at most, allowed to stretch only very limited amounts, if at all. It is believed that, at one time, there may have been a desire to “take up slack” in a sign panel fitted in the cold morning hours, and thereafter heated as the daily temperature increases. There is no confirmation of this, however, and in any event, an elastic contraction to overcome daily thermal stretching would be very small, on the order of a small fraction of an inch (e.g. one-sixteenth to one-eighth of an inch). From examining the panel illustrated in FIGS. 17-19, it was not apparent that even this small amount of stretching was possible.
As indicated in FIG. 18, the straps 3, 6 share the opening of buckle 5 with the fiberglass rib, and with wear, tend to intrude into the space intended for the rib making the assembly of FIG. 19 difficult.
Several sign panel systems are described as employing stretchable straps to secure the corners of message panels to extended ribs. For example, U.S. Pat. Nos. 6,463,687 and 6,622,409 employ shock cords at the left and right corners of the sign panel to define limits for the swiveling of the sign. The shock cords are secured to eyelets which in turn engage S-shaped hooks. The shock cords are provided with strap ends which, when pulled, fix the length of the shock cord to apply a force to the sign panel. Plastic pockets are provided to engage the ends of the supporting rods. Further, U.S. Pat. No. 5,472,162 employs a stretchable elastomeric strap which is wrapped over a molded plastic cap, fitted to the ends of cross-brace members, supporting the message panel.
Despite these advances, further improvements in sign systems have been sought. For example, improvements to lower manufacturing costs while providing improved wear resistance and compact storage are still needed.